The present invention relates to a rotational position detecting device for use in internal combustion engines. More particularly, the invention is concerned with a device for detecting rotational position of a rotating shaft of an internal combustion engine so as to produce angular position signal and reference position signal which are used for various controlling purposes such as ignition timing control and fuel injection control.
A device is known in which angular position signal and reference position signal are obtained by detecting the rotational position of a pulley fixed to a cam shaft of an engine. This type of device is disclosed for example, in JOURNAL OF NIPPONDENSO TECHNICAL DISCLOSURE No. 36-160 published July 15, 1984.
In this known device, the angular position signal and the reference position signal are derived from an angular position sensor and a reference position sensor which are so positioned as to face, respectively, angular position information section and a reference position information section formed on the pulley. In order that the clearances between the paths of movements of the information sections and respective sensors may be maintained accurately, both sensors are supported by brackets which in turn are positioned relative to the pulley with bearings disposed therebetween.
In this known rotational position detecting device, however, the sensors are arranged on the side of the pulley adjacent to the engine block. Thus, a substantial space is required between the pulley and the adjacent wall of the engine block to accommodate the sensors. As a result, the pulley has to be spaced apart from the adjacent wall of the engine block by a clearance large enough to provide the above-mentioned space. Thus, a cooperating pulley on the engine crankshaft is required to be also offset by the same amount from the engine block so as to assure that both pulleys are drivingly connected by a belt. Thus, the known device requires substantial change of the engine design with a resultant significant increase in the overall size of the engine.